The Significance of Matzah
Making a Mitzvah Part of Ourselves
The particular mitzvos associated with a holiday are intrinsically linked to its basic theme.
For example: Pesach enables us to undergo a personal exodus from Egypt by transcending our individual limits. 
Accordingly, G-d gave us the mitzvah of eating matzah to help us internalize that experience.
For, our food is assimilated into our bodies, becoming part of our flesh and blood. Eating matzah thus converts the experience of self-transcendence into an integral part of our beings.
The significance of matzah may be understood by comparing it to chametz (leaven).
Chametz, which becomes bloated as it rises, symbolizes self- inflated egotism and pride. Matzah, which remains flat and unpretentious, reflects selfless humility.
This concept is also reflected in the Torah's description of matzah as "poor man's bread";  a poor man is humble and free of arrogance.
Eating "poor man's bread" reduces our selfish tendencies.
This finds expression in the Halachah. There is no question of chametz in matzah ashirah  (lit., "rich matzah," made of flour and liquids other than water; e.g., egg matzah); nevertheless, it can not be used to fulfill the mitzvah of eating matzah. 
Since it is not "poor man's bread," it fails to convey the same spiritual message as simple matzah.
Similar, but Different
Another basic difference between chametz and matzah can be perceived by comparing the letters which make up these words.
Both words contain the letters tzaddi and mem; they differ only in that matzah is spelled with a hei, and chametz, with a ches. 
A hei and a ches are both formed of three lines, with an opening below which recalls the verse,  "Sin crouches at the opening." The letter ches is closed on all three sides, signifying no escape from the "sin at the opening."
The hei, by contrast, has an additional opening near the top. This escape hatch refers to teshuvah, the ever-open opportunity for repenting and returning to G-d. 
These two differences between chametz and matzah are interrelated.
The self-inflation symbolized by chametz is one of the fundamental causes of sin. An opinionated person is concerned primarily with his personal desires and places them above all other goals, increasing the possibility that he will sin. A person in this state will not be easily moved to teshuvah. Instead, he will seek excuses to rationalize his behavior.  For, "love covers all faults"  - especially self-love, which can blind us to even our most glaring inadequacies.
In contrast, a person whose nature reflects the qualities of matzah will be more willing to step beyond his personal wants and fulfill G-d's will. Even if he errs, he will not try to justify his behavior, but will seek to correct his faults through teshuvah.
The Bread of Faith
The Zohar  associates matzah with the quality of self- transcendence, calling it "the bread of faith."
Faith involves a commitment beyond the scope of our rational faculties. While we are obliged to understand those manifestations of Divinity that are within the grasp of our intellectual capacity, there are levels which are obviously beyond our grasp.
Faith is the only means through which we can relate to these levels.
In a personal sense, our faith is something which transcends our selves.
Often, without thinking, we make decisions that run contrary to our faith.
Although we believe in an ideal, we ignore that belief in our day-to-day life.
For example, the Talmud relates that a thief may pray to G-d for success before a burglary.  Although he believes in G-d - as is evident from his prayer - he prays for success in an act which is directly opposed to G-d's will.
Resolving an Inner Dichotomy
Most of us are not subject to such blatant errors, but each of us can find examples of how our belief in G-d fails to be realized and integrated in our daily lives.
A student of Torah might fully believe that the teachings he is studying are G-d's word, transcending human understanding.
Nevertheless, when he is actively engaged in his studies, he might find himself treating Torah as merely an intellectual exercise.
By the same token, in a dizzying moment of success, a G-d-fearing businessman may entertain the thought that "it was my strength and the power of my hand that brought me this wealth." 
Although in theory, he surely believes that "It is G-d's blessing that brings wealth,"  his belief may not affect his daily behavior and feelings.
The mitzvah of matzah is intended in part to help us overcome this inner dichotomy.
Partaking of this "food of faith" makes us conscious of the need to internalize our faith and enables us to incorporate it into our daily lives.
In light of this, we can understand the statement of our Sages,  "Chavakuk came and made them (i.e., the entire realm of the Torah and its mitzvos) depend on one mitzvah (viz., faith), as it is written, 'A righteous man lives by his faith.'" 
Rather than consider faith and observance of the mitzvos as two separate entities, Chavakuk showed that faith must pervade the totality of our service of G-d.
Faith is thus not just one mitzvah, but the force which motivates and inspires the fulfillment of all mitzvos.
Sharing the Mitzvah with Others
Given the importance of the mitzvah of eating matzah, we should make every effort to share its fulfillment with others.
In earlier times, rabbis would send matzos to all the people living in their communities.
Today, this practice should be revived by each of us within his own sphere of influence. If possible, the matzos that we send should be round and handmade, and of the kind that are known as shemurah matzah, i.e., those which from a very early stage in their preparation have been lovingly guarded against any possibility of leavening. In this way, we will ensure that many more Jews fulfill the mitzvah in the most perfect manner possible.
May these efforts lead to the fulfillment of the promise of our Sages,  "In the month of Nissan [the Jews] were redeemed and in the month of Nissan they will be redeemed" - through the coming of Mashiach speedily in our days.
Adapted from Likkutei Sichos, Vol. I, p. 129ff.; Vol. VII, p. 276
- (Back to text) See the essay entitled "The Exodus: An Experience of
the Present as well as the Past."
- (Back to text) Devarim 16:3.
- (Back to text) Though matzah ashirah is not chametz, contemporary
halachic authorities forbid its use throughout Pesach
except in extreme circumstances.
- (Back to text) Shulchan Aruch, Orach Chayim, sec. 454.
- (Back to text) See Shelah, Tractate Pesachim.
- (Back to text) Bereishis 4:7.
- (Back to text) Cf. Menachos 29b.
- (Back to text) Kuntres Uma'ayon, Discourses 16 & 17.
- (Back to text) Mishlei 10:12.
- (Back to text) Vol. II, p. 183b.
- (Back to text) Berachos 63a, as cited in Ein Yaakov. Similarly, Pachad
Yitzchak records that this is the reading in
the Portuguese edition of the Talmud.
- (Back to text) Devarim 8:17.
- (Back to text) Mishlei 10:22.
- (Back to text) Makkos 24a.
- (Back to text) Chavakuk 2:4.
- (Back to text) Rosh HaShanah 11a.